Rename BlobWriter to BlobBuilder

src/Compilers/CSharp/Portable/CodeGen/EmitArrayInitializer.cs

@@ -310,14 +310,14 @@ private ImmutableArray<byte> GetRawData(ImmutableArray<BoundExpression> initiali
             // the initial size is a guess.
             // there is no point to be precise here as MemoryStream always has N + 1 storage 
             // and will need to be trimmed regardless
-            var writer = new Cci.BlobWriter(initializers.Length * 4);
+            var writer = new Cci.BlobBuilder(initializers.Length * 4);
 
             SerializeArrayRecursive(writer, initializers);
 
             return writer.ToImmutableArray();
         }
 
-        private void SerializeArrayRecursive(Cci.BlobWriter bw, ImmutableArray<BoundExpression> inits)
+        private void SerializeArrayRecursive(Cci.BlobBuilder bw, ImmutableArray<BoundExpression> inits)
         {
             if (inits.Length != 0)
             {

src/Compilers/Core/CodeAnalysisTest/CodeAnalysisTest.csproj

@@ -25,6 +25,7 @@
     <Compile Include="AssemblyUtilitiesTests.cs" />
     <Compile Include="AsyncQueueTests.cs" />
     <Compile Include="Collections\BoxesTest.cs" />
+    <Compile Include="Collections\ByteSequenceComparerTests.cs" />
     <Compile Include="Diagnostics\DiagnosticLocalizationTests.cs" />
     <Compile Include="Emit\EmitOptionsTests.cs" />
     <Compile Include="Emit\CustomDebugInfoTests.cs" />

src/Compilers/Core/CodeAnalysisTest/Emit/CustomDebugInfoTests.cs

@@ -196,7 +196,7 @@ public void EditAndContinueLocalSlotMap_NegativeSyntaxOffsets()
             var closures = ImmutableArray<ClosureDebugInfo>.Empty;
             var lambdas = ImmutableArray<LambdaDebugInfo>.Empty;
 
-            var cmw = new Cci.BlobWriter();
+            var cmw = new Cci.BlobBuilder();
 
             new EditAndContinueMethodDebugInformation(123, slots, closures, lambdas).SerializeLocalSlots(cmw);
 
@@ -223,7 +223,7 @@ public void EditAndContinueLambdaAndClosureMap_NegativeSyntaxOffsets()
                 new LambdaDebugInfo(-50, new DebugId(1, 0), 0),
                 new LambdaDebugInfo(-180, new DebugId(2, 0), LambdaDebugInfo.StaticClosureOrdinal));
 
-            var cmw = new Cci.BlobWriter();
+            var cmw = new Cci.BlobBuilder();
 
             new EditAndContinueMethodDebugInformation(0x7b, slots, closures, lambdas).SerializeLambdaMap(cmw);
 
@@ -245,7 +245,7 @@ public void EditAndContinueLambdaAndClosureMap_NoClosures()
             var closures = ImmutableArray<ClosureDebugInfo>.Empty;
             var lambdas = ImmutableArray.Create(new LambdaDebugInfo(20, new DebugId(0, 0), LambdaDebugInfo.StaticClosureOrdinal));
 
-            var cmw = new Cci.BlobWriter();
+            var cmw = new Cci.BlobBuilder();
 
             new EditAndContinueMethodDebugInformation(-1, slots, closures, lambdas).SerializeLambdaMap(cmw);
 
@@ -268,7 +268,7 @@ public void EditAndContinueLambdaAndClosureMap_NoLambdas()
             var closures = ImmutableArray<ClosureDebugInfo>.Empty;
             var lambdas = ImmutableArray<LambdaDebugInfo>.Empty;
 
-            var cmw = new Cci.BlobWriter();
+            var cmw = new Cci.BlobBuilder();
 
             new EditAndContinueMethodDebugInformation(10, slots, closures, lambdas).SerializeLambdaMap(cmw);
 
@@ -300,7 +300,7 @@ public void EncCdiAlignment()
                 new LambdaDebugInfo(-180, new DebugId(2, 0), LambdaDebugInfo.StaticClosureOrdinal));
 
             var debugInfo = new EditAndContinueMethodDebugInformation(1, slots, closures, lambdas);
-            var records = new ArrayBuilder<Cci.BlobWriter>();
+            var records = new ArrayBuilder<Cci.BlobBuilder>();
 
             Cci.CustomDebugInfoWriter.SerializeCustomDebugInformation(debugInfo, records);
             var cdi = Cci.CustomDebugInfoWriter.SerializeCustomDebugMetadata(records);

src/Compilers/Core/CodeAnalysisTest/PEWriter/BlobWriterTests.cs

@@ -12,14 +12,14 @@ public class BlobWriterTests
     {
         private static byte[] CompressUnsignedInteger(int value)
         {
-            var writer = new BlobWriter();
+            var writer = new BlobBuilder();
             writer.WriteCompressedInteger((uint)value);
             return writer.ToArray();
         }
 
         private static byte[] CompressSignedInteger(int value)
         {
-            var writer = new BlobWriter();
+            var writer = new BlobBuilder();
             writer.WriteCompressedSignedInteger(value);
             return writer.ToArray();
         }
@@ -59,7 +59,7 @@ public void CompressSignedIntegersFromSpecExamples()
         [Fact]
         public void WritePrimitive()
         {
-            var writer = new BlobWriter(4);
+            var writer = new BlobBuilder(4);
 
             writer.WriteUInt32(0x11223344);
             writer.WriteUInt16(0x5566);
@@ -98,7 +98,7 @@ public void WritePrimitive()
         [Fact]
         public void WriteBytes1()
         {
-            var writer = new BlobWriter(4);
+            var writer = new BlobBuilder(4);
 
             writer.WriteBytes(new byte[] { 1, 2, 3, 4 });
             writer.WriteBytes(new byte[] { });
@@ -123,7 +123,7 @@ public void WriteBytes1()
         [Fact]
         public void WriteBytes2()
         {
-            var writer = new BlobWriter(4);
+            var writer = new BlobBuilder(4);
 
             writer.WriteBytes(0xff, 0);
             writer.WriteBytes(1, 4);
@@ -143,7 +143,7 @@ public void WriteBytes2()
         [Fact]
         public void WriteAlignPad()
         {
-            var writer = new BlobWriter(4);
+            var writer = new BlobBuilder(4);
 
             writer.WriteByte(0x01);
             writer.PadTo(2);
@@ -174,7 +174,7 @@ public void WriteAlignPad()
         [Fact]
         public void WriteUTF8()
         {
-            var writer = new BlobWriter(4);
+            var writer = new BlobBuilder(4);
             writer.WriteUTF8("a");
             writer.WriteUTF8("");
             writer.WriteUTF8("bc");

src/Compilers/Core/Portable/CodeGen/BasicBlock.cs

@@ -73,14 +73,14 @@ internal void Initialize(ILBuilder builder)
             //parent builder
             internal ILBuilder builder;
 
-            private Cci.BlobWriter _lazyRegularInstructions;
-            public Cci.BlobWriter Writer
+            private Cci.BlobBuilder _lazyRegularInstructions;
+            public Cci.BlobBuilder Writer
             {
                 get
                 {
                     if (_lazyRegularInstructions == null)
                     {
-                        _lazyRegularInstructions = Cci.BlobWriter.GetInstance();
+                        _lazyRegularInstructions = Cci.BlobBuilder.GetInstance();
                     }
 
                     return _lazyRegularInstructions;
@@ -248,7 +248,7 @@ private bool IsBranchToLabel
             /// <summary>
             /// Instructions that are not branches.
             /// </summary>
-            public Cci.BlobWriter RegularInstructions => _lazyRegularInstructions;
+            public Cci.BlobBuilder RegularInstructions => _lazyRegularInstructions;
 
             /// <summary>
             /// The block contains only the final branch or nothing at all
@@ -533,34 +533,17 @@ private bool TryOptimizeBranchToEquivalent(BasicBlock next, ref int delta)
             private static bool AreIdentical(BasicBlock one, BasicBlock another)
             {
                 if (one._branchCode == another._branchCode &&
-                     !one._branchCode.CanFallThrough() &&
-                     one._branchLabel == another._branchLabel)
+                    !one._branchCode.CanFallThrough() &&
+                    one._branchLabel == another._branchLabel)
                 {
                     var instr1 = one.RegularInstructions;
                     var instr2 = another.RegularInstructions;
-
-                    if (instr1 == instr2)
-                    {
-                        return true;
-                    }
-
-                    if (instr1 != null && instr2 != null && instr1.Length == instr2.Length)
-                    {
-                        for (int i = 0, l = (int)instr1.Length; i < l; i++)
-                        {
-                            if (instr1.Buffer[i] != instr2.Buffer[i])
-                            {
-                                return false;
-                            }
-                        }
-                        return true;
-                    }
+                    return instr1 == instr2 || instr1?.ContentEquals(instr2) == true;
                 }
 
                 return false;
             }
 
-
             /// <summary>
             /// Returns reversed branch operation for the current block.
             /// If no reverse opcode can be obtained Nop is returned.

src/Compilers/Core/Portable/CodeGen/ILBuilder.cs

@@ -864,7 +864,7 @@ private void RealizeBlocks()
             }
 
             // Now linearize everything with computed offsets.
-            var writer = Cci.BlobWriter.GetInstance();
+            var writer = Cci.BlobBuilder.GetInstance();
 
             for (var block = leaderBlock; block != null; block = block.NextBlock)
             {

src/Compilers/Core/Portable/CodeGen/ILBuilderEmit.cs

@@ -704,7 +704,7 @@ private void EmitDouble(double doubleValue)
             this.GetCurrentWriter().WriteInt64(int64);
         }
 
-        private static void WriteOpCode(Cci.BlobWriter writer, ILOpCode code)
+        private static void WriteOpCode(Cci.BlobBuilder writer, ILOpCode code)
         {
             var size = code.Size();
             if (size == 1)
@@ -724,7 +724,7 @@ private static void WriteOpCode(Cci.BlobWriter writer, ILOpCode code)
             }
         }
 
-        private Cci.BlobWriter GetCurrentWriter()
+        private Cci.BlobBuilder GetCurrentWriter()
         {
             return this.GetCurrentBlock().Writer;
         }

src/Compilers/Core/Portable/Collections/ByteSequenceComparer.cs

 // Copyright (c) Microsoft.  All Rights Reserved.  Licensed under the Apache License, Version 2.0.  See License.txt in the project root for license information.
 
+using System;
 using System.Collections.Generic;
 using System.Collections.Immutable;
 using System.Diagnostics;
@@ -40,21 +41,44 @@ internal static bool Equals(ImmutableArray<byte> x, ImmutableArray<byte> y)
             return true;
         }
 
-        internal static bool Equals(byte[] x, byte[] y)
+        internal static bool Equals(byte[] left, int leftStart, byte[] right, int rightStart, int length)
         {
-            if (ReferenceEquals(x, y))
+            if (left == null || right == null)
+            {
+                return ReferenceEquals(left, right);
+            }
+
+            if (ReferenceEquals(left, right) && leftStart == rightStart)
             {
                 return true;
             }
 
-            if (x == null || y == null || x.Length != y.Length)
+            for (var i = 0; i < length; i++)
+            {
+                if (left[leftStart + i] != right[rightStart + i])
+                {
+                    return false;
+                }
+            }
+
+            return true;
+        }
+
+        internal static bool Equals(byte[] left, byte[] right)
+        {
+            if (ReferenceEquals(left, right))
+            {
+                return true;
+            }
+
+            if (left == null || right == null || left.Length != right.Length)
             {
                 return false;
             }
 
-            for (var i = 0; i < x.Length; i++)
+            for (var i = 0; i < left.Length; i++)
             {
-                if (x[i] != y[i])
+                if (left[i] != right[i])
                 {
                     return false;
                 }

src/Compilers/Core/Portable/ConstantValue.cs

@@ -662,7 +662,7 @@ public bool IsNothing
             }
         }
 
-        public void Serialize(Cci.BlobWriter writer)
+        public void Serialize(Cci.BlobBuilder writer)
         {
             switch (this.Discriminator)
             {

src/Compilers/Core/Portable/Emit/EditAndContinue/DeltaMetadataWriter.cs

@@ -609,7 +609,7 @@ protected override int SerializeLocalVariablesSignature(IMethodBody body)
 
             if (localVariables.Length > 0)
             {
-                var writer = BlobWriter.GetInstance();
+                var writer = BlobBuilder.GetInstance();
                 writer.WriteByte(0x07);
                 writer.WriteCompressedInteger((uint)localVariables.Length);
 

src/Compilers/Core/Portable/Emit/EditAndContinueMethodDebugInformation.cs

@@ -121,7 +121,7 @@ private unsafe static ImmutableArray<LocalSlotDebugInfo> UncompressSlotMap(Immut
             return mapBuilder.ToImmutableAndFree();
         }
 
-        internal void SerializeLocalSlots(Cci.BlobWriter writer)
+        internal void SerializeLocalSlots(Cci.BlobBuilder writer)
         {
             int syntaxOffsetBaseline = -1;
             foreach (LocalSlotDebugInfo localSlot in this.LocalSlots)
@@ -237,7 +237,7 @@ internal void SerializeLocalSlots(Cci.BlobWriter writer)
             lambdas = lambdasBuilder.ToImmutableAndFree();
         }
 
-        internal void SerializeLambdaMap(Cci.BlobWriter writer)
+        internal void SerializeLambdaMap(Cci.BlobBuilder writer)
         {
             Debug.Assert(this.MethodOrdinal >= -1);
             writer.WriteCompressedInteger((uint)(this.MethodOrdinal + 1));

src/Compilers/Core/Portable/NativePdbWriter/PdbWriter.cs

@@ -48,7 +48,7 @@ internal sealed class PdbLogger
         // On the other hand, we do want to use a fairly large buffer as the hashing operations
         // are invoked through reflection, which is fairly slow.
         private readonly bool _logging;
-        private readonly BlobWriter _logData;
+        private readonly BlobBuilder _logData;
         private const int bufferFlushLimit = 64 * 1024;
         private readonly HashAlgorithm _hashAlgorithm;
 
@@ -57,7 +57,7 @@ internal PdbLogger(bool logging)
             _logging = logging;
             if (logging)
             {
-                _logData = BlobWriter.GetInstance();
+                _logData = BlobBuilder.GetInstance();
                 _hashAlgorithm = new SHA1CryptoServiceProvider();
                 Debug.Assert(_hashAlgorithm.SupportsTransform);
             }

src/Compilers/Core/Portable/PEWriter/BlobWriter.cs

@@ -8,17 +8,18 @@
 using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
 using System.Text;
+using Microsoft.CodeAnalysis.Collections;
 using Roslyn.Utilities;
 
 namespace Microsoft.Cci
 {
-    internal unsafe sealed class BlobWriter
+    internal unsafe sealed class BlobBuilder
     {
         private byte[] _buffer;
         private int _length;
         private int _position;
 
-        internal BlobWriter(int initialSize = 64)
+        internal BlobBuilder(int initialSize = 64)
         {
             // the writer assumes little-endian architecture:
             Debug.Assert(BitConverter.IsLittleEndian);
@@ -26,12 +27,20 @@ internal BlobWriter(int initialSize = 64)
             _buffer = new byte[initialSize];
         }
 
-        internal BlobWriter(ObjectPool<BlobWriter> pool)
+        internal BlobBuilder(ObjectPool<BlobBuilder> pool)
             : this()
         {
             _pool = pool;
         }
 
+        /// <summary>
+        /// Compares the current content of this writer with another one.
+        /// </summary>
+        public bool ContentEquals(BlobBuilder other)
+        {
+            return other != null && Length == other.Length && ByteSequenceComparer.Equals(_buffer, 0, other._buffer, 0, Length);
+        }
+
         public byte[] Buffer => _buffer;
         public int Length => _length;
 
@@ -643,7 +652,7 @@ public void WriteConstant(object value)
             }
         }
 
-        internal void WriteTo(BlobWriter stream)
+        internal void WriteTo(BlobBuilder stream)
         {
             stream.WriteBytes(_buffer, 0, _length);
         }
@@ -662,7 +671,7 @@ internal void Clear()
 
         #region Poolable
 
-        private readonly ObjectPool<BlobWriter> _pool;
+        private readonly ObjectPool<BlobBuilder> _pool;
 
         //
         // To implement Poolable, you need two things:
@@ -685,23 +694,23 @@ public void Free()
         }
 
         //2) Expose  the way to get an instance.
-        private static readonly ObjectPool<BlobWriter> s_poolInstance = CreatePool();
+        private static readonly ObjectPool<BlobBuilder> s_poolInstance = CreatePool();
 
-        public static BlobWriter GetInstance()
+        public static BlobBuilder GetInstance()
         {
             var stream = s_poolInstance.Allocate();
             return stream;
         }
 
-        public static ObjectPool<BlobWriter> CreatePool()
+        public static ObjectPool<BlobBuilder> CreatePool()
         {
             return CreatePool(32);
         }
 
-        public static ObjectPool<BlobWriter> CreatePool(int size)
+        public static ObjectPool<BlobBuilder> CreatePool(int size)
         {
-            ObjectPool<BlobWriter> pool = null;
-            pool = new ObjectPool<BlobWriter>(() => new BlobWriter(pool), size);
+            ObjectPool<BlobBuilder> pool = null;
+            pool = new ObjectPool<BlobBuilder>(() => new BlobBuilder(pool), size);
             return pool;
         }
 

src/Compilers/Core/Portable/PEWriter/CustomDebugInfoWriter.cs

@@ -78,7 +78,7 @@ public byte[] SerializeMethodDebugInfo(EmitContext context, IMethodBody methodBo
                 }
             }
 
-            var customDebugInfo = ArrayBuilder<BlobWriter>.GetInstance();
+            var customDebugInfo = ArrayBuilder<BlobBuilder>.GetInstance();
 
             SerializeIteratorClassMetadata(methodBody, customDebugInfo);
 
@@ -114,7 +114,7 @@ public byte[] SerializeMethodDebugInfo(EmitContext context, IMethodBody methodBo
         }
 
         // internal for testing
-        internal static void SerializeCustomDebugInformation(EditAndContinueMethodDebugInformation debugInfo, ArrayBuilder<BlobWriter> customDebugInfo)
+        internal static void SerializeCustomDebugInformation(EditAndContinueMethodDebugInformation debugInfo, ArrayBuilder<BlobBuilder> customDebugInfo)
         {
             if (!debugInfo.LocalSlots.IsDefaultOrEmpty)
             {
@@ -127,9 +127,9 @@ internal static void SerializeCustomDebugInformation(EditAndContinueMethodDebugI
             }
         }
 
-        private static BlobWriter SerializeRecord(byte kind, Action<BlobWriter> data)
+        private static BlobBuilder SerializeRecord(byte kind, Action<BlobBuilder> data)
         {
-            var cmw = new BlobWriter();
+            var cmw = new BlobBuilder();
             cmw.WriteByte(CDI.CdiVersion);
             cmw.WriteByte(kind);
             cmw.WriteByte(0);
@@ -160,15 +160,15 @@ private static BlobWriter SerializeRecord(byte kind, Action<BlobWriter> data)
             return cmw;
         }
 
-        private static void SerializeIteratorClassMetadata(IMethodBody methodBody, ArrayBuilder<BlobWriter> customDebugInfo)
+        private static void SerializeIteratorClassMetadata(IMethodBody methodBody, ArrayBuilder<BlobBuilder> customDebugInfo)
         {
             SerializeReferenceToIteratorClass(methodBody.StateMachineTypeName, customDebugInfo);
         }
 
-        private static void SerializeReferenceToIteratorClass(string iteratorClassName, ArrayBuilder<BlobWriter> customDebugInfo)
+        private static void SerializeReferenceToIteratorClass(string iteratorClassName, ArrayBuilder<BlobBuilder> customDebugInfo)
         {
             if (iteratorClassName == null) return;
-            var cmw = new BlobWriter();
+            var cmw = new BlobBuilder();
             cmw.WriteByte(CDI.CdiVersion);
             cmw.WriteByte(CDI.CdiKindForwardIterator);
             cmw.Align(4);
@@ -182,7 +182,7 @@ private static void SerializeReferenceToIteratorClass(string iteratorClassName,
             customDebugInfo.Add(cmw);
         }
 
-        private static void SerializeStateMachineLocalScopes(IMethodBody methodBody, ArrayBuilder<BlobWriter> customDebugInfo)
+        private static void SerializeStateMachineLocalScopes(IMethodBody methodBody, ArrayBuilder<BlobBuilder> customDebugInfo)
         {
             var scopes = methodBody.StateMachineHoistedLocalScopes;
             if (scopes.IsDefaultOrEmpty)
@@ -191,7 +191,7 @@ private static void SerializeStateMachineLocalScopes(IMethodBody methodBody, Arr
             }
 
             uint numberOfScopes = (uint)scopes.Length;
-            var cmw = new BlobWriter();
+            var cmw = new BlobBuilder();
             cmw.WriteByte(CDI.CdiVersion);
             cmw.WriteByte(CDI.CdiKindStateMachineHoistedLocalScopes);
             cmw.Align(4);
@@ -215,7 +215,7 @@ private static void SerializeStateMachineLocalScopes(IMethodBody methodBody, Arr
             customDebugInfo.Add(cmw);
         }
 
-        private static void SerializeDynamicLocalInfo(IMethodBody methodBody, ArrayBuilder<BlobWriter> customDebugInfo)
+        private static void SerializeDynamicLocalInfo(IMethodBody methodBody, ArrayBuilder<BlobBuilder> customDebugInfo)
         {
             if (!methodBody.HasDynamicLocalVariables)
             {
@@ -248,7 +248,7 @@ private static void SerializeDynamicLocalInfo(IMethodBody methodBody, ArrayBuild
             Debug.Assert(dynamicLocals.Any()); // There must be at least one dynamic local if this point is reached
 
             const int blobSize = 200;//DynamicAttribute - 64, DynamicAttributeLength - 4, SlotIndex -4, IdentifierName - 128
-            var cmw = new BlobWriter();
+            var cmw = new BlobBuilder();
             cmw.WriteByte(CDI.CdiVersion);
             cmw.WriteByte(CDI.CdiKindDynamicLocals);
             cmw.Align(4);
@@ -307,18 +307,18 @@ private static void SerializeDynamicLocalInfo(IMethodBody methodBody, ArrayBuild
         }
 
         // internal for testing
-        internal static byte[] SerializeCustomDebugMetadata(ArrayBuilder<BlobWriter> recordWriters)
+        internal static byte[] SerializeCustomDebugMetadata(ArrayBuilder<BlobBuilder> recordWriters)
         {
             if (recordWriters.Count == 0)
             {
                 return null;
             }
 
-            BlobWriter cmw = BlobWriter.GetInstance();
+            BlobBuilder cmw = BlobBuilder.GetInstance();
             cmw.WriteByte(CDI.CdiVersion);
             cmw.WriteByte((byte)recordWriters.Count); // count
             cmw.Align(4);
-            foreach (BlobWriter recordWriter in recordWriters)
+            foreach (BlobBuilder recordWriter in recordWriters)
             {
                 recordWriter.WriteTo(cmw);
             }
@@ -328,7 +328,7 @@ internal static byte[] SerializeCustomDebugMetadata(ArrayBuilder<BlobWriter> rec
             return result;
         }
 
-        private void SerializeNamespaceScopeMetadata(EmitContext context, IMethodBody methodBody, ArrayBuilder<BlobWriter> customDebugInfo)
+        private void SerializeNamespaceScopeMetadata(EmitContext context, IMethodBody methodBody, ArrayBuilder<BlobBuilder> customDebugInfo)
         {
             if (context.Module.GenerateVisualBasicStylePdb)
             {
@@ -343,7 +343,7 @@ private void SerializeNamespaceScopeMetadata(EmitContext context, IMethodBody me
             }
 
             List<ushort> usingCounts = new List<ushort>();
-            var cmw = new BlobWriter();
+            var cmw = new BlobBuilder();
             for (IImportScope scope = methodBody.ImportScope; scope != null; scope = scope.Parent)
             {
                 usingCounts.Add((ushort)scope.GetUsedNamespaces().Length);
@@ -421,9 +421,9 @@ private bool ShouldForwardToPreviousMethodWithUsingInfo(EmitContext context, IMe
             return s1 == s2;
         }
 
-        private void SerializeReferenceToMethodWithModuleInfo(ArrayBuilder<BlobWriter> customDebugInfo)
+        private void SerializeReferenceToMethodWithModuleInfo(ArrayBuilder<BlobBuilder> customDebugInfo)
         {
-            BlobWriter cmw = new BlobWriter(12);
+            BlobBuilder cmw = new BlobBuilder(12);
             cmw.WriteByte(CDI.CdiVersion);
             cmw.WriteByte(CDI.CdiKindForwardToModuleInfo);
             cmw.Align(4);
@@ -432,9 +432,9 @@ private void SerializeReferenceToMethodWithModuleInfo(ArrayBuilder<BlobWriter> c
             customDebugInfo.Add(cmw);
         }
 
-        private void SerializeReferenceToPreviousMethodWithUsingInfo(ArrayBuilder<BlobWriter> customDebugInfo)
+        private void SerializeReferenceToPreviousMethodWithUsingInfo(ArrayBuilder<BlobBuilder> customDebugInfo)
         {
-            BlobWriter cmw = new BlobWriter(12);
+            BlobBuilder cmw = new BlobBuilder(12);
             cmw.WriteByte(CDI.CdiVersion);
             cmw.WriteByte(CDI.CdiKindForwardInfo);
             cmw.Align(4);

src/Compilers/Core/Portable/PEWriter/ManagedResource.cs

@@ -32,7 +32,7 @@ internal ManagedResource(string name, bool isPublic, Func<Stream> streamProvider
             _isPublic = isPublic;
         }
 
-        public void WriteData(BlobWriter resourceWriter)
+        public void WriteData(BlobBuilder resourceWriter)
         {
             if (_fileReference == null)
             {

src/Compilers/Core/Portable/PEWriter/MetadataHeapsBuilder.cs

@@ -98,13 +98,13 @@ internal sealed class MetadataHeapsBuilder
 
         // #US heap
         private readonly Dictionary<string, int> _userStrings = new Dictionary<string, int>();
-        private readonly BlobWriter _userStringWriter = new BlobWriter(1024);
+        private readonly BlobBuilder _userStringWriter = new BlobBuilder(1024);
         private readonly int _userStringHeapStartOffset;
 
         // #String heap
         private Dictionary<string, StringIdx> _strings = new Dictionary<string, StringIdx>(128);
         private int[] _stringIndexToHeapPositionMap;
-        private BlobWriter _stringWriter;
+        private BlobBuilder _stringWriter;
         private readonly int _stringHeapStartOffset;
 
         // #Blob heap
@@ -114,7 +114,7 @@ internal sealed class MetadataHeapsBuilder
 
         // #GUID heap
         private readonly Dictionary<Guid, int> _guids = new Dictionary<Guid, int>();
-        private readonly BlobWriter _guidWriter = new BlobWriter(16); // full metadata has just a single guid
+        private readonly BlobBuilder _guidWriter = new BlobBuilder(16); // full metadata has just a single guid
 
         private bool _streamsAreComplete;
 
@@ -144,7 +144,7 @@ internal sealed class MetadataHeapsBuilder
              _guidWriter.WriteBytes(0, guidHeapStartOffset);
         }
 
-        internal BlobIdx GetBlobIndex(BlobWriter stream)
+        internal BlobIdx GetBlobIndex(BlobBuilder stream)
         {
             // TODO: avoid making a copy if the blob exists in the index
             return GetBlobIndex(stream.ToImmutableArray());
@@ -160,7 +160,7 @@ internal BlobIdx GetBlobIndex(ImmutableArray<byte> blob)
                 index = new BlobIdx(_blobHeapSize);
                 _blobs.Add(blob, index);
 
-                _blobHeapSize += BlobWriter.GetCompressedIntegerSize(blob.Length) + blob.Length;
+                _blobHeapSize += BlobBuilder.GetCompressedIntegerSize(blob.Length) + blob.Length;
             }
             
             return index;
@@ -174,7 +174,7 @@ public BlobIdx GetConstantBlobIndex(object value)
                 return this.GetBlobIndex(str);
             }
 
-            var writer = new BlobWriter();
+            var writer = new BlobBuilder();
             writer.WriteConstant(value);
             return this.GetBlobIndex(writer);
         }
@@ -361,7 +361,7 @@ private void SerializeStringHeap()
             sorted.Sort(new SuffixSort());
             _strings = null;
 
-            _stringWriter = new BlobWriter(1024);
+            _stringWriter = new BlobBuilder(1024);
 
             // Create VirtIdx to Idx map and add entry for empty string
             _stringIndexToHeapPositionMap = new int[sorted.Count + 1];
@@ -420,7 +420,7 @@ public int Compare(KeyValuePair<string, StringIdx> xPair, KeyValuePair<string, S
             }
         }
 
-        public void WriteTo(BlobWriter writer, out int guidHeapStartOffset)
+        public void WriteTo(BlobBuilder writer, out int guidHeapStartOffset)
         {
             WriteAligned(_stringWriter, writer);
             WriteAligned(_userStringWriter, writer);
@@ -431,7 +431,7 @@ public void WriteTo(BlobWriter writer, out int guidHeapStartOffset)
             WriteAlignedBlobHeap(writer);
         }
 
-        private void WriteAlignedBlobHeap(BlobWriter writer)
+        private void WriteAlignedBlobHeap(BlobBuilder writer)
         {
             int heapStart = writer.Position;
 
@@ -459,7 +459,7 @@ private void WriteAlignedBlobHeap(BlobWriter writer)
             writer.WriteBytes(0, BitArithmeticUtilities.Align(_blobHeapSize, 4) - _blobHeapSize);
         }
 
-        private static void WriteAligned(BlobWriter source, BlobWriter target)
+        private static void WriteAligned(BlobBuilder source, BlobBuilder target)
         {
             int length = source.Length;
             source.WriteTo(target);

src/Compilers/Core/Portable/PEWriter/MetadataWriter.PortablePdb.cs

@@ -185,7 +185,7 @@ private void SerializeMethodDebugInfo(IMethodBody bodyOpt, int methodRid, int lo
 
         private BlobIdx SerializeLocalConstantSignature(ILocalDefinition localConstant)
         {
-            var writer = new BlobWriter();
+            var writer = new BlobBuilder();
 
             // CustomMod*
             SerializeCustomModifiers(localConstant.CustomModifiers, writer);
@@ -267,7 +267,7 @@ private enum HasCustomDebugInformationTag
 
         private const int ModuleImportScopeRid = 1;
 
-        private void SerializeImport(BlobWriter writer, AssemblyReferenceAlias alias)
+        private void SerializeImport(BlobBuilder writer, AssemblyReferenceAlias alias)
         {
             // <import> ::= AliasAssemblyReference <alias> <target-assembly>
             writer.WriteByte((byte)ImportDefinitionKind.AliasAssemblyReference);
@@ -275,7 +275,7 @@ private void SerializeImport(BlobWriter writer, AssemblyReferenceAlias alias)
             writer.WriteCompressedInteger((uint)GetOrAddAssemblyRefIndex(alias.Assembly));
         }
 
-        private void SerializeImport(BlobWriter writer, UsedNamespaceOrType import)
+        private void SerializeImport(BlobBuilder writer, UsedNamespaceOrType import)
         {
             if (import.TargetXmlNamespaceOpt != null)
             {
@@ -358,7 +358,7 @@ private void SerializeImport(BlobWriter writer, UsedNamespaceOrType import)
         private void DefineModuleImportScope()
         {
             // module-level import scope:
-            var writer = new BlobWriter();
+            var writer = new BlobBuilder();
 
             SerializeModuleDefaultNamespace();
 
@@ -406,7 +406,7 @@ private int GetImportScopeIndex(IImportScope scope, Dictionary<IImportScope, int
 
         private BlobIdx SerializeImportsBlob(IImportScope scope)
         {
-            var writer = new BlobWriter();
+            var writer = new BlobBuilder();
 
             foreach (UsedNamespaceOrType import in scope.GetUsedNamespaces())
             {
@@ -510,7 +510,7 @@ private void SerializeAsyncMethodSteppingInfo(AsyncMethodBodyDebugInfo asyncInfo
             Debug.Assert(asyncInfo.ResumeOffsets.Length == asyncInfo.YieldOffsets.Length);
             Debug.Assert(asyncInfo.CatchHandlerOffset >= -1);
 
-            var writer = new BlobWriter();
+            var writer = new BlobBuilder();
 
             writer.WriteUInt32((uint)((long)asyncInfo.CatchHandlerOffset + 1));
 
@@ -537,7 +537,7 @@ private void SerializeStateMachineLocalScopes(IMethodBody methodBody, int method
                 return;
             }
 
-            var writer = new BlobWriter();
+            var writer = new BlobBuilder();
 
             foreach (var scope in scopes)
             {
@@ -564,7 +564,7 @@ private BlobIdx SerializeSequencePoints(int localSignatureRowId, ImmutableArray<
                 return default(BlobIdx);
             }
 
-            var writer = new BlobWriter();
+            var writer = new BlobBuilder();
 
             int previousNonHiddenStartLine = -1;
             int previousNonHiddenStartColumn = -1;
@@ -625,7 +625,7 @@ private BlobIdx SerializeSequencePoints(int localSignatureRowId, ImmutableArray<
             return _debugHeapsOpt.GetBlobIndex(writer);
         }
 
-        private void SerializeDeltaLinesAndColumns(BlobWriter writer, SequencePoint sequencePoint)
+        private void SerializeDeltaLinesAndColumns(BlobBuilder writer, SequencePoint sequencePoint)
         {
             int deltaLines = sequencePoint.EndLine - sequencePoint.StartLine;
             int deltaColumns = sequencePoint.EndColumn - sequencePoint.StartColumn;
@@ -677,7 +677,7 @@ private BlobIdx SerializeDocumentName(string name)
         {
             Debug.Assert(name != null);
 
-            var writer = new BlobWriter();
+            var writer = new BlobBuilder();
 
             int c1 = Count(name, Separator1[0]);
             int c2 = Count(name, Separator2[0]);
@@ -719,7 +719,7 @@ private void SerializeEncMethodDebugInformation(IMethodBody methodBody, int meth
 
             if (!encInfo.LocalSlots.IsDefaultOrEmpty)
             {
-                var writer = new BlobWriter();
+                var writer = new BlobBuilder();
 
                 encInfo.SerializeLocalSlots(writer);
 
@@ -733,7 +733,7 @@ private void SerializeEncMethodDebugInformation(IMethodBody methodBody, int meth
 
             if (!encInfo.Lambdas.IsDefaultOrEmpty)
             {
-                var writer = new BlobWriter();
+                var writer = new BlobBuilder();
 
                 encInfo.SerializeLambdaMap(writer);
 
@@ -750,7 +750,7 @@ private void SerializeEncMethodDebugInformation(IMethodBody methodBody, int meth
 
         #region Table Serialization
 
-        private void SerializeDocumentTable(BlobWriter writer, MetadataSizes metadataSizes)
+        private void SerializeDocumentTable(BlobBuilder writer, MetadataSizes metadataSizes)
         {
             foreach (var row in _documentTable)
             {
@@ -761,7 +761,7 @@ private void SerializeDocumentTable(BlobWriter writer, MetadataSizes metadataSiz
             }
         }
 
-        private void SerializeMethodBodyTable(BlobWriter writer, MetadataSizes metadataSizes)
+        private void SerializeMethodBodyTable(BlobBuilder writer, MetadataSizes metadataSizes)
         {
             foreach (var row in _methodBodyTable)
             {
@@ -769,7 +769,7 @@ private void SerializeMethodBodyTable(BlobWriter writer, MetadataSizes metadataS
             }
         }
 
-        private void SerializeLocalScopeTable(BlobWriter writer, MetadataSizes metadataSizes)
+        private void SerializeLocalScopeTable(BlobBuilder writer, MetadataSizes metadataSizes)
         {
             foreach (var row in _localScopeTable)
             {
@@ -782,7 +782,7 @@ private void SerializeLocalScopeTable(BlobWriter writer, MetadataSizes metadataS
             }
         }
 
-        private void SerializeLocalVariableTable(BlobWriter writer, MetadataSizes metadataSizes)
+        private void SerializeLocalVariableTable(BlobBuilder writer, MetadataSizes metadataSizes)
         {
             foreach (var row in _localVariableTable)
             {
@@ -792,7 +792,7 @@ private void SerializeLocalVariableTable(BlobWriter writer, MetadataSizes metada
             }
         }
 
-        private void SerializeLocalConstantTable(BlobWriter writer, MetadataSizes metadataSizes)
+        private void SerializeLocalConstantTable(BlobBuilder writer, MetadataSizes metadataSizes)
         {
             foreach (var row in _localConstantTable)
             {
@@ -801,7 +801,7 @@ private void SerializeLocalConstantTable(BlobWriter writer, MetadataSizes metada
             }
         }
 
-        private void SerializeImportScopeTable(BlobWriter writer, MetadataSizes metadataSizes)
+        private void SerializeImportScopeTable(BlobBuilder writer, MetadataSizes metadataSizes)
         {
             foreach (var row in _importScopeTable)
             {
@@ -810,7 +810,7 @@ private void SerializeImportScopeTable(BlobWriter writer, MetadataSizes metadata
             }
         }
 
-        private void SerializeStateMachineMethodTable(BlobWriter writer, MetadataSizes metadataSizes)
+        private void SerializeStateMachineMethodTable(BlobBuilder writer, MetadataSizes metadataSizes)
         {
             foreach (var row in _stateMachineMethodTable)
             {
@@ -819,7 +819,7 @@ private void SerializeStateMachineMethodTable(BlobWriter writer, MetadataSizes m
             }
         }
 
-        private void SerializeCustomDebugInformationTable(BlobWriter writer, MetadataSizes metadataSizes)
+        private void SerializeCustomDebugInformationTable(BlobBuilder writer, MetadataSizes metadataSizes)
         {
             // sort by Parent, Kind
             _customDebugInformationTable.Sort(CustomDebugInformationRowComparer.Instance);

src/Compilers/Core/Portable/PEWriter/MetadataWriter.cs

@@ -769,7 +769,7 @@ private BlobIdx GetCustomAttributeSignatureIndex(ICustomAttribute customAttribut
                 return result;
             }
 
-            var writer = new BlobWriter();
+            var writer = new BlobBuilder();
             this.SerializeCustomAttributeSignature(customAttribute, false, writer);
             result = heaps.GetBlobIndex(writer);
             _customAttributeSignatureIndex.Add(customAttribute, result);
@@ -885,7 +885,7 @@ internal BlobIdx GetFieldSignatureIndex(IFieldReference fieldReference)
                 return result;
             }
 
-            var writer = BlobWriter.GetInstance();
+            var writer = BlobBuilder.GetInstance();
             this.SerializeFieldSignature(fieldReference, writer);
             result = heaps.GetBlobIndex(writer);
             _fieldSignatureIndex.Add(fieldReference, result);
@@ -992,7 +992,7 @@ private uint GetImplementationCodedIndex(INamespaceTypeReference namespaceRef)
             return 0;
         }
 
-        private static uint GetManagedResourceOffset(ManagedResource resource, BlobWriter resourceWriter)
+        private static uint GetManagedResourceOffset(ManagedResource resource, BlobBuilder resourceWriter)
         {
             if (resource.ExternalFile != null)
             {
@@ -1145,7 +1145,7 @@ internal BlobIdx GetMethodInstanceSignatureIndex(IGenericMethodInstanceReference
                 return result;
             }
 
-            var writer = BlobWriter.GetInstance();
+            var writer = BlobBuilder.GetInstance();
             writer.WriteByte(0x0A);
             writer.WriteCompressedInteger(methodInstanceReference.GetGenericMethod(Context).GenericParameterCount);
             foreach (ITypeReference typeref in methodInstanceReference.GetGenericArguments(Context))
@@ -1167,7 +1167,7 @@ private BlobIdx GetMarshallingDescriptorIndex(IMarshallingInformation marshallin
                 return result;
             }
 
-            var writer = BlobWriter.GetInstance();
+            var writer = BlobBuilder.GetInstance();
             this.SerializeMarshallingDescriptor(marshallingInformation, writer);
             result = heaps.GetBlobIndex(writer);
             _marshallingDescriptorIndex.Add(marshallingInformation, result);
@@ -1227,7 +1227,7 @@ private BlobIdx GetMethodSignatureIndexAndBlob(IMethodReference methodReference,
                 return existing.Key;
             }
 
-            var writer = BlobWriter.GetInstance();
+            var writer = BlobBuilder.GetInstance();
             this.SerializeSignature(methodReference, methodReference.GenericParameterCount, methodReference.ExtraParameters, writer);
 
             signatureBlob = writer.ToImmutableArray();
@@ -1239,7 +1239,7 @@ private BlobIdx GetMethodSignatureIndexAndBlob(IMethodReference methodReference,
 
         private BlobIdx GetGenericMethodInstanceIndex(IGenericMethodInstanceReference genericMethodInstanceReference)
         {
-            var writer = BlobWriter.GetInstance();
+            var writer = BlobBuilder.GetInstance();
             this.SerializeGenericMethodInstanceSignature(writer, genericMethodInstanceReference);
             BlobIdx result = heaps.GetBlobIndex(writer);
             writer.Free();
@@ -1310,7 +1310,7 @@ internal PrimitiveTypeCode GetConstantTypeCode(ILocalDefinition constant)
 
         private BlobIdx GetPermissionSetIndex(ImmutableArray<ICustomAttribute> permissionSet)
         {
-            var writer = BlobWriter.GetInstance();
+            var writer = BlobBuilder.GetInstance();
             BlobIdx result;
             try
             {
@@ -1356,7 +1356,7 @@ private BlobIdx GetPropertySignatureIndex(IPropertyDefinition propertyDef)
                 return existing.Key;
             }
 
-            var writer = BlobWriter.GetInstance();
+            var writer = BlobBuilder.GetInstance();
             this.SerializeSignature(propertyDef, 0, ImmutableArray<IParameterTypeInformation>.Empty, writer);
             var blob = writer.ToImmutableArray();
             var result = heaps.GetBlobIndex(blob);
@@ -1852,7 +1852,7 @@ internal BlobIdx GetTypeSpecSignatureIndex(ITypeReference typeReference)
                 return result;
             }
 
-            var writer = BlobWriter.GetInstance();
+            var writer = BlobBuilder.GetInstance();
             this.SerializeTypeReference(typeReference, writer, false, true);
             result = heaps.GetBlobIndex(writer);
             _typeSpecSignatureIndex.Add(typeReference, result);
@@ -1928,7 +1928,7 @@ internal int GetTokenForDefinition(IDefinition definition)
             throw ExceptionUtilities.Unreachable;
         }
 
-        private void SerializeCustomModifiers(ImmutableArray<ICustomModifier> customModifiers, BlobWriter writer)
+        private void SerializeCustomModifiers(ImmutableArray<ICustomModifier> customModifiers, BlobBuilder writer)
         {
             foreach (ICustomModifier customModifier in customModifiers)
             {
@@ -1936,7 +1936,7 @@ private void SerializeCustomModifiers(ImmutableArray<ICustomModifier> customModi
             }
         }
 
-        private void SerializeCustomModifier(ICustomModifier customModifier, BlobWriter writer)
+        private void SerializeCustomModifier(ICustomModifier customModifier, BlobBuilder writer)
         {
             if (customModifier.IsOptional)
             {
@@ -1950,7 +1950,7 @@ private void SerializeCustomModifier(ICustomModifier customModifier, BlobWriter
             writer.WriteCompressedInteger(this.GetTypeDefOrRefCodedIndex(customModifier.GetModifier(Context), true));
         }
 
-        private void SerializeMetadataHeader(BlobWriter writer, MetadataSizes metadataSizes)
+        private void SerializeMetadataHeader(BlobBuilder writer, MetadataSizes metadataSizes)
         {
             int startOffset = writer.Position;
 
@@ -2016,7 +2016,7 @@ private void SerializeMetadataHeader(BlobWriter writer, MetadataSizes metadataSi
             Debug.Assert(endOffset - startOffset == metadataSizes.MetadataHeaderSize);
         }
 
-        private static void SerializeStreamHeader(ref int offsetFromStartOfMetadata, int alignedStreamSize, string streamName, BlobWriter writer)
+        private static void SerializeStreamHeader(ref int offsetFromStartOfMetadata, int alignedStreamSize, string streamName, BlobBuilder writer)
         {
             // 4 for the first uint (offset), 4 for the second uint (padded size), length of stream name + 1 for null terminator (then padded)
             int sizeOfStreamHeader = MetadataSizes.GetMetadataStreamHeaderSize(streamName);
@@ -2041,10 +2041,10 @@ public void WriteMetadataAndIL(PdbWriter pdbWriterOpt, Stream metadataStream, St
             pdbWriterOpt?.SetMetadataEmitter(this);
 
             // TODO: we can precalculate the exact size of IL stream
-            var ilWriter = new BlobWriter(1024);
-            var metadataWriter = new BlobWriter(4 * 1024);
-            var mappedFieldDataWriter = new BlobWriter(0);
-            var managedResourceDataWriter = new BlobWriter(0);
+            var ilWriter = new BlobBuilder(1024);
+            var metadataWriter = new BlobBuilder(4 * 1024);
+            var mappedFieldDataWriter = new BlobBuilder(0);
+            var managedResourceDataWriter = new BlobBuilder(0);
 
             // Add 4B of padding to the start of the separated IL stream, 
             // so that method RVAs, which are offsets to this stream, are never 0.
@@ -2061,7 +2061,7 @@ public void WriteMetadataAndIL(PdbWriter pdbWriterOpt, Stream metadataStream, St
 
             SerializeMetadataAndIL(
                 metadataWriter,
-                default(BlobWriter),
+                default(BlobBuilder),
                 pdbWriterOpt,
                 ilWriter,
                 mappedFieldDataWriter,
@@ -2081,12 +2081,12 @@ public void WriteMetadataAndIL(PdbWriter pdbWriterOpt, Stream metadataStream, St
         }
 
         public void SerializeMetadataAndIL(
-            BlobWriter metadataWriter,
-            BlobWriter debugMetadataWriterOpt,
+            BlobBuilder metadataWriter,
+            BlobBuilder debugMetadataWriterOpt,
             PdbWriter nativePdbWriterOpt,
-            BlobWriter ilWriter,
-            BlobWriter mappedFieldDataWriter,
-            BlobWriter managedResourceDataWriter,
+            BlobBuilder ilWriter,
+            BlobBuilder mappedFieldDataWriter,
+            BlobBuilder managedResourceDataWriter,
             int methodBodyStreamRva,
             Func<MetadataSizes, int> calculateMappedFieldDataStreamRva,
             out int moduleVersionIdOffsetInMetadataStream,
@@ -2197,7 +2197,7 @@ private static int CalculateStrongNameSignatureSize(IModule module)
         }
 
         private void SerializeMetadata(
-            BlobWriter metadataWriter,
+            BlobBuilder metadataWriter,
             MetadataSizes metadataSizes,
             int methodBodyStreamRva,
             int mappedFieldDataStreamRva,
@@ -2243,7 +2243,7 @@ private int GetModuleVersionGuidOffsetInMetadataStream(int guidHeapOffsetInMetad
         }
 
         private void SerializeMetadataTables(
-            BlobWriter writer,
+            BlobBuilder writer,
             MetadataSizes metadataSizes, 
             int methodBodyStreamRva, 
             int mappedFieldDataStreamRva)
@@ -2480,7 +2480,7 @@ private int GetModuleVersionGuidOffsetInMetadataStream(int guidHeapOffsetInMetad
             Debug.Assert(metadataSizes.MetadataTableStreamSize == endPosition - startPosition);
         }
 
-        private void PopulateTables(int[] methodBodyRvas, BlobWriter mappedFieldDataWriter, BlobWriter resourceWriter)
+        private void PopulateTables(int[] methodBodyRvas, BlobBuilder mappedFieldDataWriter, BlobBuilder resourceWriter)
         {
             this.PopulateAssemblyRefTableRows();
             this.PopulateAssemblyTableRows();
@@ -3144,7 +3144,7 @@ private struct FieldMarshalRow { public uint Parent; public BlobIdx NativeType;
 
         private readonly List<FieldMarshalRow> _fieldMarshalTable = new List<FieldMarshalRow>();
 
-        private void PopulateFieldRvaTableRows(BlobWriter mappedFieldDataWriter)
+        private void PopulateFieldRvaTableRows(BlobBuilder mappedFieldDataWriter)
         {
             foreach (IFieldDefinition fieldDef in this.GetFieldDefs())
             {
@@ -3329,7 +3329,7 @@ private struct InterfaceImplRow { public uint Class; public uint Interface; }
 
         private readonly List<InterfaceImplRow> _interfaceImplTable = new List<InterfaceImplRow>();
 
-        private void PopulateManifestResourceTableRows(BlobWriter resourceDataWriter)
+        private void PopulateManifestResourceTableRows(BlobBuilder resourceDataWriter)
         {
             foreach (var resource in this.module.GetResources(Context))
             {
@@ -3740,7 +3740,7 @@ private struct TypeSpecRow { public BlobIdx Signature; }
 
         private readonly List<TypeSpecRow> _typeSpecTable = new List<TypeSpecRow>();
 
-        private void SerializeTablesHeader(BlobWriter writer, MetadataSizes metadataSizes)
+        private void SerializeTablesHeader(BlobBuilder writer, MetadataSizes metadataSizes)
         {
             int startPosition = writer.Position;
 
@@ -3780,7 +3780,7 @@ private void SerializeTablesHeader(BlobWriter writer, MetadataSizes metadataSize
             Debug.Assert(metadataSizes.CalculateTableStreamHeaderSize() == endPosition - startPosition);
         }
 
-        private static void SerializeStandalonePdbStream(BlobWriter writer, MetadataSizes metadataSizes, int entryPointToken)
+        private static void SerializeStandalonePdbStream(BlobBuilder writer, MetadataSizes metadataSizes, int entryPointToken)
         {
             int startPosition = writer.Position;
 
@@ -3793,7 +3793,7 @@ private static void SerializeStandalonePdbStream(BlobWriter writer, MetadataSize
             Debug.Assert(metadataSizes.CalculateStandalonePdbStreamSize() == endPosition - startPosition);
         }
 
-        private static void SerializeRowCounts(BlobWriter writer, ImmutableArray<int> rowCounts, ulong includeTables)
+        private static void SerializeRowCounts(BlobBuilder writer, ImmutableArray<int> rowCounts, ulong includeTables)
         {
             for (int i = 0; i < rowCounts.Length; i++)
             {
@@ -3808,7 +3808,7 @@ private static void SerializeRowCounts(BlobWriter writer, ImmutableArray<int> ro
             }
         }
 
-        private void SerializeModuleTable(BlobWriter writer, MetadataSizes metadataSizes, MetadataHeapsBuilder heaps)
+        private void SerializeModuleTable(BlobBuilder writer, MetadataSizes metadataSizes, MetadataHeapsBuilder heaps)
         {
             writer.WriteUInt16(_moduleRow.Generation);
             writer.WriteReference((uint)heaps.ResolveStringIndex(_moduleRow.Name), metadataSizes.StringIndexSize);
@@ -3817,7 +3817,7 @@ private void SerializeModuleTable(BlobWriter writer, MetadataSizes metadataSizes
             writer.WriteReference((uint)_moduleRow.EncBaseId, metadataSizes.GuidIndexSize);
         }
 
-        private void SerializeEncLogTable(BlobWriter writer)
+        private void SerializeEncLogTable(BlobBuilder writer)
         {
             foreach (EncLogRow encLog in _encLogTable)
             {
@@ -3826,7 +3826,7 @@ private void SerializeEncLogTable(BlobWriter writer)
             }
         }
 
-        private void SerializeEncMapTable(BlobWriter writer)
+        private void SerializeEncMapTable(BlobBuilder writer)
         {
             foreach (EncMapRow encMap in _encMapTable)
             {
@@ -3834,7 +3834,7 @@ private void SerializeEncMapTable(BlobWriter writer)
             }
         }
 
-        private void SerializeTypeRefTable(BlobWriter writer, MetadataSizes metadataSizes)
+        private void SerializeTypeRefTable(BlobBuilder writer, MetadataSizes metadataSizes)
         {
             foreach (TypeRefRow typeRef in _typeRefTable)
             {
@@ -3844,7 +3844,7 @@ private void SerializeTypeRefTable(BlobWriter writer, MetadataSizes metadataSize
             }
         }
 
-        private void SerializeTypeDefTable(BlobWriter writer, MetadataSizes metadataSizes)
+        private void SerializeTypeDefTable(BlobBuilder writer, MetadataSizes metadataSizes)
         {
             foreach (TypeDefRow typeDef in _typeDefTable)
             {
@@ -3857,7 +3857,7 @@ private void SerializeTypeDefTable(BlobWriter writer, MetadataSizes metadataSize
             }
         }
 
-        private void SerializeFieldTable(BlobWriter writer, MetadataSizes metadataSizes)
+        private void SerializeFieldTable(BlobBuilder writer, MetadataSizes metadataSizes)
         {
             foreach (FieldDefRow fieldDef in _fieldDefTable)
             {
@@ -3867,7 +3867,7 @@ private void SerializeFieldTable(BlobWriter writer, MetadataSizes metadataSizes)
             }
         }
 
-        private void SerializeMethodDefTable(BlobWriter writer, MetadataSizes metadataSizes, int methodBodyStreamRva)
+        private void SerializeMethodDefTable(BlobBuilder writer, MetadataSizes metadataSizes, int methodBodyStreamRva)
         {
             foreach (MethodRow method in _methodTable)
             {
@@ -3888,7 +3888,7 @@ private void SerializeMethodDefTable(BlobWriter writer, MetadataSizes metadataSi
             }
         }
 
-        private void SerializeParamTable(BlobWriter writer, MetadataSizes metadataSizes)
+        private void SerializeParamTable(BlobBuilder writer, MetadataSizes metadataSizes)
         {
             foreach (ParamRow param in _paramTable)
             {
@@ -3898,7 +3898,7 @@ private void SerializeParamTable(BlobWriter writer, MetadataSizes metadataSizes)
             }
         }
 
-        private void SerializeInterfaceImplTable(BlobWriter writer, MetadataSizes metadataSizes)
+        private void SerializeInterfaceImplTable(BlobBuilder writer, MetadataSizes metadataSizes)
         {
             foreach (InterfaceImplRow interfaceImpl in _interfaceImplTable)
             {
@@ -3907,7 +3907,7 @@ private void SerializeInterfaceImplTable(BlobWriter writer, MetadataSizes metada
             }
         }
 
-        private void SerializeMemberRefTable(BlobWriter writer, MetadataSizes metadataSizes)
+        private void SerializeMemberRefTable(BlobBuilder writer, MetadataSizes metadataSizes)
         {
             foreach (MemberRefRow memberRef in _memberRefTable)
             {
@@ -3917,7 +3917,7 @@ private void SerializeMemberRefTable(BlobWriter writer, MetadataSizes metadataSi
             }
         }
 
-        private void SerializeConstantTable(BlobWriter writer, MetadataSizes metadataSizes)
+        private void SerializeConstantTable(BlobBuilder writer, MetadataSizes metadataSizes)
         {
             foreach (ConstantRow constant in _constantTable)
             {
@@ -3928,7 +3928,7 @@ private void SerializeConstantTable(BlobWriter writer, MetadataSizes metadataSiz
             }
         }
 
-        private void SerializeCustomAttributeTable(BlobWriter writer, MetadataSizes metadataSizes)
+        private void SerializeCustomAttributeTable(BlobBuilder writer, MetadataSizes metadataSizes)
         {
             foreach (CustomAttributeRow customAttribute in _customAttributeTable)
             {
@@ -3938,7 +3938,7 @@ private void SerializeCustomAttributeTable(BlobWriter writer, MetadataSizes meta
             }
         }
 
-        private void SerializeFieldMarshalTable(BlobWriter writer, MetadataSizes metadataSizes)
+        private void SerializeFieldMarshalTable(BlobBuilder writer, MetadataSizes metadataSizes)
         {
             foreach (FieldMarshalRow fieldMarshal in _fieldMarshalTable)
             {
@@ -3947,7 +3947,7 @@ private void SerializeFieldMarshalTable(BlobWriter writer, MetadataSizes metadat
             }
         }
 
-        private void SerializeDeclSecurityTable(BlobWriter writer, MetadataSizes metadataSizes)
+        private void SerializeDeclSecurityTable(BlobBuilder writer, MetadataSizes metadataSizes)
         {
             foreach (DeclSecurityRow declSecurity in _declSecurityTable)
             {
@@ -3957,7 +3957,7 @@ private void SerializeDeclSecurityTable(BlobWriter writer, MetadataSizes metadat
             }
         }
 
-        private void SerializeClassLayoutTable(BlobWriter writer, MetadataSizes metadataSizes)
+        private void SerializeClassLayoutTable(BlobBuilder writer, MetadataSizes metadataSizes)
         {
             foreach (ClassLayoutRow classLayout in _classLayoutTable)
             {
@@ -3967,7 +3967,7 @@ private void SerializeClassLayoutTable(BlobWriter writer, MetadataSizes metadata
             }
         }
 
-        private void SerializeFieldLayoutTable(BlobWriter writer, MetadataSizes metadataSizes)
+        private void SerializeFieldLayoutTable(BlobBuilder writer, MetadataSizes metadataSizes)
         {
             foreach (FieldLayoutRow fieldLayout in _fieldLayoutTable)
             {
@@ -3976,7 +3976,7 @@ private void SerializeFieldLayoutTable(BlobWriter writer, MetadataSizes metadata
             }
         }
 
-        private void SerializeStandAloneSigTable(BlobWriter writer, MetadataSizes metadataSizes)
+        private void SerializeStandAloneSigTable(BlobBuilder writer, MetadataSizes metadataSizes)
         {
             foreach (BlobIdx blobIndex in this.GetStandAloneSignatures())
             {
@@ -3984,7 +3984,7 @@ private void SerializeStandAloneSigTable(BlobWriter writer, MetadataSizes metada
             }
         }
 
-        private void SerializeEventMapTable(BlobWriter writer, MetadataSizes metadataSizes)
+        private void SerializeEventMapTable(BlobBuilder writer, MetadataSizes metadataSizes)
         {
             foreach (EventMapRow eventMap in _eventMapTable)
             {
@@ -3993,7 +3993,7 @@ private void SerializeEventMapTable(BlobWriter writer, MetadataSizes metadataSiz
             }
         }
 
-        private void SerializeEventTable(BlobWriter writer, MetadataSizes metadataSizes)
+        private void SerializeEventTable(BlobBuilder writer, MetadataSizes metadataSizes)
         {
             foreach (EventRow eventRow in _eventTable)
             {
@@ -4003,7 +4003,7 @@ private void SerializeEventTable(BlobWriter writer, MetadataSizes metadataSizes)
             }
         }
 
-        private void SerializePropertyMapTable(BlobWriter writer, MetadataSizes metadataSizes)
+        private void SerializePropertyMapTable(BlobBuilder writer, MetadataSizes metadataSizes)
         {
             foreach (PropertyMapRow propertyMap in _propertyMapTable)
             {
@@ -4012,7 +4012,7 @@ private void SerializePropertyMapTable(BlobWriter writer, MetadataSizes metadata
             }
         }
 
-        private void SerializePropertyTable(BlobWriter writer, MetadataSizes metadataSizes)
+        private void SerializePropertyTable(BlobBuilder writer, MetadataSizes metadataSizes)
         {
             foreach (PropertyRow property in _propertyTable)
             {
@@ -4022,7 +4022,7 @@ private void SerializePropertyTable(BlobWriter writer, MetadataSizes metadataSiz
             }
         }
 
-        private void SerializeMethodSemanticsTable(BlobWriter writer, MetadataSizes metadataSizes)
+        private void SerializeMethodSemanticsTable(BlobBuilder writer, MetadataSizes metadataSizes)
         {
             foreach (MethodSemanticsRow methodSemantic in _methodSemanticsTable)
             {
@@ -4032,7 +4032,7 @@ private void SerializeMethodSemanticsTable(BlobWriter writer, MetadataSizes meta
             }
         }
 
-        private void SerializeMethodImplTable(BlobWriter writer, MetadataSizes metadataSizes)
+        private void SerializeMethodImplTable(BlobBuilder writer, MetadataSizes metadataSizes)
         {
             foreach (MethodImplRow methodImpl in _methodImplTable)
             {
@@ -4042,7 +4042,7 @@ private void SerializeMethodImplTable(BlobWriter writer, MetadataSizes metadataS
             }
         }
 
-        private void SerializeModuleRefTable(BlobWriter writer, MetadataSizes metadataSizes)
+        private void SerializeModuleRefTable(BlobBuilder writer, MetadataSizes metadataSizes)
         {
             foreach (ModuleRefRow moduleRef in _moduleRefTable)
             {
@@ -4050,7 +4050,7 @@ private void SerializeModuleRefTable(BlobWriter writer, MetadataSizes metadataSi
             }
         }
 
-        private void SerializeTypeSpecTable(BlobWriter writer, MetadataSizes metadataSizes)
+        private void SerializeTypeSpecTable(BlobBuilder writer, MetadataSizes metadataSizes)
         {
             foreach (TypeSpecRow typeSpec in _typeSpecTable)
             {
@@ -4058,7 +4058,7 @@ private void SerializeTypeSpecTable(BlobWriter writer, MetadataSizes metadataSiz
             }
         }
 
-        private void SerializeImplMapTable(BlobWriter writer, MetadataSizes metadataSizes)
+        private void SerializeImplMapTable(BlobBuilder writer, MetadataSizes metadataSizes)
         {
             foreach (ImplMapRow implMap in _implMapTable)
             {
@@ -4069,7 +4069,7 @@ private void SerializeImplMapTable(BlobWriter writer, MetadataSizes metadataSize
             }
         }
 
-        private void SerializeFieldRvaTable(BlobWriter writer, MetadataSizes metadataSizes, int mappedFieldDataStreamRva)
+        private void SerializeFieldRvaTable(BlobBuilder writer, MetadataSizes metadataSizes, int mappedFieldDataStreamRva)
         {
             foreach (FieldRvaRow fieldRva in _fieldRvaTable)
             {
@@ -4078,7 +4078,7 @@ private void SerializeFieldRvaTable(BlobWriter writer, MetadataSizes metadataSiz
             }
         }
 
-        private void SerializeAssemblyTable(BlobWriter writer, MetadataSizes metadataSizes)
+        private void SerializeAssemblyTable(BlobBuilder writer, MetadataSizes metadataSizes)
         {
             IAssembly assembly = this.module.AsAssembly;
             if (assembly == null)
@@ -4098,7 +4098,7 @@ private void SerializeAssemblyTable(BlobWriter writer, MetadataSizes metadataSiz
             writer.WriteReference((uint)heaps.ResolveStringIndex(_assemblyCulture), metadataSizes.StringIndexSize);
         }
 
-        private void SerializeAssemblyRefTable(BlobWriter writer, MetadataSizes metadataSizes)
+        private void SerializeAssemblyRefTable(BlobBuilder writer, MetadataSizes metadataSizes)
         {
             foreach (AssemblyRefTableRow assemblyRef in _assemblyRefTable)
             {
@@ -4125,7 +4125,7 @@ private void SerializeAssemblyRefTable(BlobWriter writer, MetadataSizes metadata
             }
         }
 
-        private void SerializeFileTable(BlobWriter writer, MetadataSizes metadataSizes)
+        private void SerializeFileTable(BlobBuilder writer, MetadataSizes metadataSizes)
         {
             foreach (FileTableRow fileReference in _fileTable)
             {
@@ -4135,7 +4135,7 @@ private void SerializeFileTable(BlobWriter writer, MetadataSizes metadataSizes)
             }
         }
 
-        private void SerializeExportedTypeTable(BlobWriter writer, MetadataSizes metadataSizes)
+        private void SerializeExportedTypeTable(BlobBuilder writer, MetadataSizes metadataSizes)
         {
             foreach (ExportedTypeRow exportedType in _exportedTypeTable)
             {
@@ -4147,7 +4147,7 @@ private void SerializeExportedTypeTable(BlobWriter writer, MetadataSizes metadat
             }
         }
 
-        private void SerializeManifestResourceTable(BlobWriter writer, MetadataSizes metadataSizes)
+        private void SerializeManifestResourceTable(BlobBuilder writer, MetadataSizes metadataSizes)
         {
             foreach (ManifestResourceRow manifestResource in _manifestResourceTable)
             {
@@ -4158,7 +4158,7 @@ private void SerializeManifestResourceTable(BlobWriter writer, MetadataSizes met
             }
         }
 
-        private void SerializeNestedClassTable(BlobWriter writer, MetadataSizes metadataSizes)
+        private void SerializeNestedClassTable(BlobBuilder writer, MetadataSizes metadataSizes)
         {
             foreach (NestedClassRow nestedClass in _nestedClassTable)
             {
@@ -4167,7 +4167,7 @@ private void SerializeNestedClassTable(BlobWriter writer, MetadataSizes metadata
             }
         }
 
-        private void SerializeGenericParamTable(BlobWriter writer, MetadataSizes metadataSizes)
+        private void SerializeGenericParamTable(BlobBuilder writer, MetadataSizes metadataSizes)
         {
             foreach (GenericParamRow genericParam in _genericParamTable)
             {
@@ -4178,7 +4178,7 @@ private void SerializeGenericParamTable(BlobWriter writer, MetadataSizes metadat
             }
         }
 
-        private void SerializeMethodSpecTable(BlobWriter writer, MetadataSizes metadataSizes)
+        private void SerializeMethodSpecTable(BlobBuilder writer, MetadataSizes metadataSizes)
         {
             foreach (MethodSpecRow methodSpec in _methodSpecTable)
             {
@@ -4187,7 +4187,7 @@ private void SerializeMethodSpecTable(BlobWriter writer, MetadataSizes metadataS
             }
         }
 
-        private void SerializeGenericParamConstraintTable(BlobWriter writer, MetadataSizes metadataSizes)
+        private void SerializeGenericParamConstraintTable(BlobBuilder writer, MetadataSizes metadataSizes)
         {
             foreach (GenericParamConstraintRow genericParamConstraint in _genericParamConstraintTable)
             {
@@ -4196,7 +4196,7 @@ private void SerializeGenericParamConstraintTable(BlobWriter writer, MetadataSiz
             }
         }
 
-        private int[] SerializeMethodBodies(BlobWriter writer, PdbWriter pdbWriterOpt)
+        private int[] SerializeMethodBodies(BlobBuilder writer, PdbWriter pdbWriterOpt)
         {
             CustomDebugInfoWriter customDebugInfoWriter = (pdbWriterOpt != null) ? new CustomDebugInfoWriter(pdbWriterOpt) : null;
 
@@ -4253,7 +4253,7 @@ private int[] SerializeMethodBodies(BlobWriter writer, PdbWriter pdbWriterOpt)
             return rvas;
         }
 
-        private int SerializeMethodBody(IMethodBody methodBody, BlobWriter writer, uint localSignatureToken)
+        private int SerializeMethodBody(IMethodBody methodBody, BlobBuilder writer, uint localSignatureToken)
         {
             int ilLength = methodBody.IL.Length;
             uint numberOfExceptionHandlers = (uint)methodBody.ExceptionRegions.Length;
@@ -4322,7 +4322,7 @@ protected virtual int SerializeLocalVariablesSignature(IMethodBody body)
                 return 0;
             }
 
-            var writer = BlobWriter.GetInstance();
+            var writer = BlobBuilder.GetInstance();
             writer.WriteByte(0x07);
             writer.WriteCompressedInteger((uint)localVariables.Length);
             foreach (ILocalDefinition local in localVariables)
@@ -4337,7 +4337,7 @@ protected virtual int SerializeLocalVariablesSignature(IMethodBody body)
             return signatureIndex;
         }
 
-        protected void SerializeLocalVariableSignature(BlobWriter writer, ILocalDefinition local)
+        protected void SerializeLocalVariableSignature(BlobBuilder writer, ILocalDefinition local)
         {
             if (module.IsPlatformType(local.Type, PlatformType.SystemTypedReference))
             {
@@ -4366,7 +4366,7 @@ protected void SerializeLocalVariableSignature(BlobWriter writer, ILocalDefiniti
 
         internal int SerializeLocalConstantStandAloneSignature(ILocalDefinition localConstant)
         {
-            var writer = BlobWriter.GetInstance();
+            var writer = BlobBuilder.GetInstance();
             writer.WriteByte(0x06);
 
             foreach (ICustomModifier modifier in localConstant.CustomModifiers)
@@ -4532,7 +4532,7 @@ private byte[] SerializeMethodBodyIL(IMethodBody methodBody)
             return methodBodyIL;
         }
 
-        private void SerializeMethodBodyExceptionHandlerTable(IMethodBody methodBody, uint numberOfExceptionHandlers, BlobWriter writer)
+        private void SerializeMethodBodyExceptionHandlerTable(IMethodBody methodBody, uint numberOfExceptionHandlers, BlobBuilder writer)
         {
             var regions = methodBody.ExceptionRegions;
             bool useSmallExceptionHeaders = MayUseSmallExceptionHeaders(numberOfExceptionHandlers, regions);
@@ -4558,7 +4558,7 @@ private void SerializeMethodBodyExceptionHandlerTable(IMethodBody methodBody, ui
             }
         }
 
-        private void SerializeExceptionRegion(ExceptionHandlerRegion region, bool useSmallExceptionHeaders, BlobWriter writer)
+        private void SerializeExceptionRegion(ExceptionHandlerRegion region, bool useSmallExceptionHeaders, BlobBuilder writer)
         {
             writer.WriteUInt16((ushort)region.HandlerKind);
 
@@ -4621,7 +4621,7 @@ private static bool MayUseSmallExceptionHeaders(uint numberOfExceptionHandlers,
             return true;
         }
 
-        private void SerializeParameterInformation(IParameterTypeInformation parameterTypeInformation, BlobWriter writer)
+        private void SerializeParameterInformation(IParameterTypeInformation parameterTypeInformation, BlobBuilder writer)
         {
             bool hasByRefBeforeCustomModifiers = parameterTypeInformation.HasByRefBeforeCustomModifiers;
 
@@ -4645,14 +4645,14 @@ private void SerializeParameterInformation(IParameterTypeInformation parameterTy
             this.SerializeTypeReference(parameterTypeInformation.GetType(Context), writer, false, true);
         }
 
-        private void SerializeFieldSignature(IFieldReference fieldReference, BlobWriter writer)
+        private void SerializeFieldSignature(IFieldReference fieldReference, BlobBuilder writer)
         {
             writer.WriteByte(0x06);
 
             this.SerializeTypeReference(fieldReference.GetType(Context), writer, false, true);
         }
 
-        private void SerializeGenericMethodInstanceSignature(BlobWriter writer, IGenericMethodInstanceReference genericMethodInstanceReference)
+        private void SerializeGenericMethodInstanceSignature(BlobBuilder writer, IGenericMethodInstanceReference genericMethodInstanceReference)
         {
             writer.WriteByte(0x0a);
             writer.WriteCompressedInteger(genericMethodInstanceReference.GetGenericMethod(Context).GenericParameterCount);
@@ -4662,7 +4662,7 @@ private void SerializeGenericMethodInstanceSignature(BlobWriter writer, IGeneric
             }
         }
 
-        private void SerializeCustomAttributeSignature(ICustomAttribute customAttribute, bool writeOnlyNamedArguments, BlobWriter writer)
+        private void SerializeCustomAttributeSignature(ICustomAttribute customAttribute, bool writeOnlyNamedArguments, BlobBuilder writer)
         {
             if (!writeOnlyNamedArguments)
             {
@@ -4711,7 +4711,7 @@ private void SerializeCustomAttributeSignature(ICustomAttribute customAttribute,
             }
         }
 
-        private void SerializeMetadataExpression(BlobWriter writer, IMetadataExpression expression, ITypeReference targetType)
+        private void SerializeMetadataExpression(BlobBuilder writer, IMetadataExpression expression, ITypeReference targetType)
         {
             IMetadataCreateArray a = expression as IMetadataCreateArray;
             if (a != null)
@@ -4795,7 +4795,7 @@ private void SerializeMetadataExpression(BlobWriter writer, IMetadataExpression
             }
         }
 
-        private void SerializeMarshallingDescriptor(IMarshallingInformation marshallingInformation, BlobWriter writer)
+        private void SerializeMarshallingDescriptor(IMarshallingInformation marshallingInformation, BlobBuilder writer)
         {
             writer.WriteCompressedInteger((uint)marshallingInformation.UnmanagedType);
             switch (marshallingInformation.UnmanagedType)
@@ -4890,7 +4890,7 @@ private void SerializeMarshallingDescriptor(IMarshallingInformation marshallingI
             }
         }
 
-        private void SerializeTypeName(ITypeReference typeReference, BlobWriter writer)
+        private void SerializeTypeName(ITypeReference typeReference, BlobBuilder writer)
         {
             writer.WriteSerializedString(typeReference.GetSerializedTypeName(this.Context));
         }
@@ -4943,7 +4943,7 @@ internal static string StrongName(IAssemblyReference assemblyReference)
             return pooled.ToStringAndFree();
         }
 
-        private void SerializePermissionSet(IEnumerable<ICustomAttribute> permissionSet, BlobWriter writer)
+        private void SerializePermissionSet(IEnumerable<ICustomAttribute> permissionSet, BlobBuilder writer)
         {
             EmitContext context = this.Context;
             foreach (ICustomAttribute customAttribute in permissionSet)
@@ -4961,7 +4961,7 @@ private void SerializePermissionSet(IEnumerable<ICustomAttribute> permissionSet,
                 }
 
                 writer.WriteSerializedString(typeName);
-                var customAttributeWriter = new BlobWriter();
+                var customAttributeWriter = new BlobBuilder();
                 this.SerializeCustomAttributeSignature(customAttribute, true, customAttributeWriter);
                 writer.WriteCompressedInteger((uint)customAttributeWriter.Length);
                 customAttributeWriter.WriteTo(writer);
@@ -4969,7 +4969,7 @@ private void SerializePermissionSet(IEnumerable<ICustomAttribute> permissionSet,
             // TODO: xml for older platforms
         }
 
-        private void SerializeSignature(ISignature signature, ushort genericParameterCount, ImmutableArray<IParameterTypeInformation> extraArgumentTypes, BlobWriter writer)
+        private void SerializeSignature(ISignature signature, ushort genericParameterCount, ImmutableArray<IParameterTypeInformation> extraArgumentTypes, BlobBuilder writer)
         {
             byte header = (byte)signature.CallingConvention;
             if (signature is IPropertyDefinition)
@@ -5014,7 +5014,7 @@ private void SerializeSignature(ISignature signature, ushort genericParameterCou
             }
         }
 
-        private void SerializeTypeReference(ITypeReference typeReference, BlobWriter writer, bool noTokens, bool treatRefAsPotentialTypeSpec)
+        private void SerializeTypeReference(ITypeReference typeReference, BlobBuilder writer, bool noTokens, bool treatRefAsPotentialTypeSpec)
         {
             while (true)
             {

src/Compilers/Core/Portable/PEWriter/PeWriter.cs

@@ -39,7 +39,7 @@ internal sealed class PeWriter
         private readonly IEnumerable<IWin32Resource> _nativeResourcesOpt;
         private readonly ResourceSection _nativeResourceSectionOpt;
 
-        private readonly BlobWriter _win32ResourceWriter = new BlobWriter(1024);
+        private readonly BlobBuilder _win32ResourceWriter = new BlobBuilder(1024);
         
         private PeWriter(
             ModulePropertiesForSerialization properties,
@@ -87,12 +87,12 @@ internal sealed class PeWriter
         private bool WritePeToStream(MetadataWriter mdWriter, Func<Stream> getPeStream, Func<Stream> getPortablePdbStreamOpt, PdbWriter nativePdbWriterOpt)
         {
             // TODO: we can precalculate the exact size of IL stream
-            var ilWriter = new BlobWriter(32 * 1024);
-            var metadataWriter = new BlobWriter(16 * 1024);
-            var mappedFieldDataWriter = new BlobWriter();
-            var managedResourceWriter = new BlobWriter(1024);
+            var ilWriter = new BlobBuilder(32 * 1024);
+            var metadataWriter = new BlobBuilder(16 * 1024);
+            var mappedFieldDataWriter = new BlobBuilder();
+            var managedResourceWriter = new BlobBuilder(1024);
 
-            var debugMetadataWriterOpt = (getPortablePdbStreamOpt != null) ? new BlobWriter(16 * 1024) : null;
+            var debugMetadataWriterOpt = (getPortablePdbStreamOpt != null) ? new BlobBuilder(16 * 1024) : null;
 
             nativePdbWriterOpt?.SetMetadataEmitter(mdWriter);
 
@@ -824,7 +824,7 @@ private void SerializeWin32Resources(IEnumerable<IWin32Resource> theResources, i
                 languageDirectory.Entries.Add(r);
             }
 
-            var dataWriter = BlobWriter.GetInstance();
+            var dataWriter = BlobBuilder.GetInstance();
 
             //'dataWriter' is where opaque resource data goes as well as strings that are used as type or name identifiers
             this.WriteDirectory(typeDirectory, _win32ResourceWriter, 0, 0, sizeOfDirectoryTree, resourcesRva, dataWriter);
@@ -838,7 +838,7 @@ private void SerializeWin32Resources(IEnumerable<IWin32Resource> theResources, i
             dataWriter.Free();
         }
 
-        private void WriteDirectory(Directory directory, BlobWriter writer, uint offset, uint level, uint sizeOfDirectoryTree, int virtualAddressBase, BlobWriter dataWriter)
+        private void WriteDirectory(Directory directory, BlobBuilder writer, uint offset, uint level, uint sizeOfDirectoryTree, int virtualAddressBase, BlobBuilder dataWriter)
         {
             writer.WriteUInt32(0); // Characteristics
             writer.WriteUInt32(0); // Timestamp
@@ -1009,7 +1009,7 @@ private void SerializeWin32Resources(ResourceSection resourceSections, int resou
 
         private void WriteHeaders(Stream peStream, NtHeader ntHeader, CoffHeader coffHeader, List<SectionHeader> sectionHeaders, out long ntHeaderTimestampPosition)
         {
-            var writer = new BlobWriter(1024);
+            var writer = new BlobBuilder(1024);
 
             // MS-DOS stub (128 bytes)
             writer.WriteBytes(s_dosHeader);
@@ -1129,7 +1129,7 @@ private void WriteHeaders(Stream peStream, NtHeader ntHeader, CoffHeader coffHea
             writer.WriteTo(peStream);
         }
 
-        private static void WriteSectionHeader(SectionHeader sectionHeader, BlobWriter writer)
+        private static void WriteSectionHeader(SectionHeader sectionHeader, BlobBuilder writer)
         {
             if (sectionHeader.VirtualSize == 0)
             {
@@ -1165,10 +1165,10 @@ private static void WriteSectionHeader(SectionHeader sectionHeader, BlobWriter w
             int importTableRva,
             int importAddressTableRva,
             int entryPointToken,
-            BlobWriter metadataWriter,
-            BlobWriter ilWriter,
-            BlobWriter mappedFieldDataWriter,
-            BlobWriter managedResourceWriter,
+            BlobBuilder metadataWriter,
+            BlobBuilder ilWriter,
+            BlobBuilder mappedFieldDataWriter,
+            BlobBuilder managedResourceWriter,
             MetadataSizes metadataSizes,
             ContentId nativePdbContentId,
             ContentId portablePdbContentId,
@@ -1227,7 +1227,7 @@ private static void WriteSectionHeader(SectionHeader sectionHeader, BlobWriter w
 
         private void WriteImportAddressTable(Stream peStream, int importTableRva)
         {
-            var writer = new BlobWriter(SizeOfImportAddressTable);
+            var writer = new BlobBuilder(SizeOfImportAddressTable);
             int ilRVA = importTableRva + 40;
             int hintRva = ilRVA + (_is32bit ? 12 : 16);
 
@@ -1249,7 +1249,7 @@ private void WriteImportAddressTable(Stream peStream, int importTableRva)
 
         private void WriteImportTable(Stream peStream, int importTableRva, int importAddressTableRva)
         {
-            var writer = new BlobWriter(SizeOfImportTable);
+            var writer = new BlobBuilder(SizeOfImportTable);
             int ilRVA = importTableRva + 40;
             int hintRva = ilRVA + (_is32bit ? 12 : 16);
             int nameRva = hintRva + 12 + 2;
@@ -1291,7 +1291,7 @@ private void WriteImportTable(Stream peStream, int importTableRva, int importAdd
 
         private static void WriteNameTable(Stream peStream)
         {
-            var writer = new BlobWriter(SizeOfNameTable);
+            var writer = new BlobBuilder(SizeOfNameTable);
             foreach (char ch in CorEntryPointDll)
             {
                 writer.WriteByte((byte)ch);
@@ -1306,7 +1306,7 @@ private static void WriteNameTable(Stream peStream)
 
         private static void WriteCorHeader(Stream peStream, CorHeader corHeader)
         {
-            var writer = new BlobWriter(CorHeaderSize);
+            var writer = new BlobBuilder(CorHeaderSize);
             writer.WriteUInt32(CorHeaderSize);
             writer.WriteUInt16(corHeader.MajorRuntimeVersion);
             writer.WriteUInt16(corHeader.MinorRuntimeVersion); 
@@ -1344,7 +1344,7 @@ private void WriteDebugTable(Stream peStream, SectionHeader textSection, Content
         {
             Debug.Assert(nativePdbContentId.IsDefault ^ portablePdbContentId.IsDefault);
 
-            var writer = new BlobWriter();
+            var writer = new BlobBuilder();
 
             // characteristics:
             writer.WriteUInt32(0);
@@ -1397,7 +1397,7 @@ private void WriteDebugTable(Stream peStream, SectionHeader textSection, Content
 
         private void WriteRuntimeStartupStub(Stream peStream, int importAddressTableRva)
         {
-            var writer = new BlobWriter(16);
+            var writer = new BlobBuilder(16);
             // entry point code, consisting of a jump indirect to _CorXXXMain
             if (_is32bit)
             {
@@ -1433,7 +1433,7 @@ private void WriteRuntimeStartupStub(Stream peStream, int importAddressTableRva)
         private void WriteRelocSection(Stream peStream, SectionHeader relocSection, int entryPointAddress)
         {
             peStream.Position = relocSection.PointerToRawData;
-            var writer = new BlobWriter(relocSection.SizeOfRawData);
+            var writer = new BlobBuilder(relocSection.SizeOfRawData);
             writer.WriteUInt32((((uint)entryPointAddress + 2) / 0x1000) * 0x1000);
             writer.WriteUInt32(_properties.Requires64bits && !_properties.RequiresAmdInstructionSet ? 14u : 12u);
             uint offsetWithinPage = ((uint)entryPointAddress + 2) % 0x1000;

src/Compilers/VisualBasic/Portable/CodeGen/EmitArrayInitializer.vb

@@ -264,14 +264,14 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.CodeGen
             ' the initial size is a guess.
             ' there is no point to be precise here as MemoryStream always has N + 1 storage 
             ' and will need to be trimmed regardless
-            Dim writer As New Cci.BlobWriter(initializers.Length * 4)
+            Dim writer As New Cci.BlobBuilder(initializers.Length * 4)
 
             SerializeArrayRecursive(writer, initializers)
 
             Return writer.ToImmutableArray()
         End Function
 
-        Private Sub SerializeArrayRecursive(bw As Cci.BlobWriter, inits As ImmutableArray(Of BoundExpression))
+        Private Sub SerializeArrayRecursive(bw As Cci.BlobBuilder, inits As ImmutableArray(Of BoundExpression))
             If inits.Length <> 0 Then
                 If inits(0).Kind = BoundKind.ArrayInitialization Then
                     For Each init In inits

src/Test/Utilities/ILBuilderVisualizer.cs

@@ -187,10 +187,10 @@ private static void DumpBlockIL(ILBuilder.BasicBlock block, StringBuilder sb)
 
         private static void DumpBasicBlockIL(ILBuilder.BasicBlock block, StringBuilder sb)
         {
-            var instrCnt = (int)block.RegularInstructionsLength;
+            var instrCnt = block.RegularInstructionsLength;
             if (instrCnt != 0)
             {
-                byte[] il = block.RegularInstructions.Buffer;
+                byte[] il = block.RegularInstructions.ToArray();
                 new ILBuilderVisualizer(block.builder.module).DumpILBlock(il, instrCnt, sb, SpecializedCollections.EmptyArray<ILVisualizer.HandlerSpan>(), block.Start);
             }
 
@@ -219,8 +219,8 @@ private static void DumpBasicBlockIL(ILBuilder.BasicBlock block, StringBuilder s
 
         private static void DumpSwitchBlockIL(ILBuilder.SwitchBlock block, StringBuilder sb)
         {
-            byte[] il = block.RegularInstructions.Buffer;
-            new ILBuilderVisualizer(block.builder.module).DumpILBlock(il, (int)block.RegularInstructionsLength, sb, SpecializedCollections.EmptyArray<ILVisualizer.HandlerSpan>(), block.Start);
+            byte[] il = block.RegularInstructions.ToArray();
+            new ILBuilderVisualizer(block.builder.module).DumpILBlock(il, il.Length, sb, SpecializedCollections.EmptyArray<HandlerSpan>(), block.Start);
 
             // switch (N, t1, t2... tN)
             //  IL ==> ILOpCode.Switch < unsigned int32 > < int32 >... < int32 >